/*
 * Copyright (c) 2004-2022, University of Oslo
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * Neither the name of the HISP project nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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 */
package org.hisp.dhis.monitoring.prometheus.config;

import java.util.function.Function;
import java.util.function.Supplier;
import org.springframework.util.Assert;

/**
 * Base class for properties to config adapters.
 *
 * @param <T> The properties type
 * @author Phillip Webb
 * @author Nikolay Rybak
 */
public class PropertiesConfigAdapter<T> {

  private T properties;

  /**
   * Create a new {@link PropertiesConfigAdapter} instance.
   *
   * @param properties the source properties
   */
  public PropertiesConfigAdapter(T properties) {
    Assert.notNull(properties, "Properties must not be null");
    this.properties = properties;
  }

  /**
   * Get the value from the properties or use a fallback from the {@code defaults}.
   *
   * @param getter the getter for the properties
   * @param fallback the fallback method, usually super interface method reference
   * @param <V> the value type
   * @return the property or fallback value
   */
  protected final <V> V get(Function<T, V> getter, Supplier<V> fallback) {
    V value = getter.apply(properties);
    return (value != null ? value : fallback.get());
  }
}
